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Design >> Analog Design >> rapid poweron opamps
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Message started by vivkr on Mar 22^nd, 2006, 1:57am

Title: rapid poweron opamps
Post by vivkr on Mar 22^nd, 2006, 1:57am

Hi,

I am wondering if there is a good way to turn on a high-gain opamp (DC gain ~ 90 dB) from
a standby condition to fully accurate operation mode (fully loaded) in a short duration
(~100ns).

Any ideas will be appreciated? I am interested in using the opamp in a circuit which works
in burst-mode, and is usually turned off or placed in standby to save power.

Regards
Vivek

Title: Re: rapid poweron opamps
Post by Paul on Mar 23^rd, 2006, 12:44pm

Hi Vivek,

100ns seems quite short for complete wake-up, but you may find some interesting ideas in the domain of switched op-amp circuits introduced by Crols and Steyaert (that's at least my earliest reference). In this technique, some switches in switched-capacitor circuits are moved inside the amplifier, which output is switched to high impedance in one clock period. It may be worth having a look at the following paper:
Switched-opamp: an approach to realize full CMOS switched-capacitor circuits at very low power supply voltages
Crols, J.; Steyaert, M.;
IEEE Journal of Solid-State Circuits
Volume 29, Issue 8, Aug. 1994 Page(s):936 - 942

Paul